A conventional inkjet printing system includes a printhead, an ink supply which supplies liquid ink to the printhead, and an electronic controller which controls the printhead. The printhead ejects ink drops through a plurality of orifices or nozzles and toward a print medium, such as a sheet of paper, so as to print onto the print medium. Typically, the orifices are arranged in one or more arrays such that properly sequenced ejection of ink from the orifices causes characters or other images to be printed upon the print medium as the printhead and the print medium are moved relative to each other.
Typically, the printhead ejects the ink drops through the nozzles by rapidly heating a small volume of ink located in vaporization chambers with small electric heaters, such as thin film resisters. Heating the ink causes the ink to vaporize and be ejected from the nozzles. Typically, for one dot of ink, a remote printhead controller typically located as part of the processing electronics of a printer, controls the timing and activation of an electrical current from a power supply external to the printhead with a fire pulse. The electrical current is passed through a selected thin film resister to heat the ink in a corresponding selected vaporization chamber.
In one type of inkjet printing system, printheads receive fire signals containing fire pulses from the electronic controller. In one arrangement, the fire signal is fed directly to the nozzles in the printhead. In another arrangement, the fire signal is latched in the printhead, and the latched version of the fire signal is fed to the nozzles to control the ejection of ink drops from the nozzles.
In either of the above two arrangements, the electronic controller of the printer maintains control of all timing related to the fire signal. The timing related to the fire signal primarily refers to the actual width of the fire pulse and the point in time at which the fire pulse occurs. The electronic controller controlling the timing related to the fire signal works well for printheads capable of printing only a single column at a time, because such printheads only need one fire signal to the printhead to control the ejection of ink drops from the printhead.
One proposed printhead has the capability of printing multiple columns of the same color or multiple columns of different colors simultaneously.
In one arrangement, commonly referred to as a wide-array inkjet printing system, a plurality of individual printheads, also referred to as printhead dies, are mounted on a single carrier. In one proposed arrangement, a wide-array inkjet printing system includes printheads which have the capability of printing multiple columns of the same color or multiple columns of different colors simultaneously. In any of these arrangements, a number of nozzles and, therefore, an overall number of ink drops which can be ejected per second is increased. Since the overall number of drops which can be ejected per second is increased, printing speed can be increased with a wide-array inkjet printing system and/or printheads having the capability of printing multiple columns simultaneously.
The energy requirements of different printheads and/or different print columns can possibly require a different fire pulse width for each printhead and/or print column due to processing/manufacturing variability. In this case, the number of fire signals necessary for the inkjet printing system increases significantly. For example, a 4-color integrated printhead requires four fire signals in order to independently control each color. If six of the example 4-color integrated printheads are disposed on a single carrier to form a print bar array in a wide-array inkjet printing system, the number of required fire signals increases to 24.
For reasons stated above and for other reasons presented in greater detail in the Description of the Preferred Embodiment section of the present specification, a wide-array inkjet printing system and/or a printhead having the capability of printing multiple columns is desired which minimizes the number of fire signals provided from the electronic controller to the printhead(s).